This invention relates in general to vehicle headliners, and in particular to a headliner having improved structural integrity.
Virtually all passenger vehicles include a headliner attached under the roof structure of the vehicle. The headliner functions as a decorative trim piece and also preferably provides sound absorption or attenuation to help reduce the noise level within the vehicle. The headliner may also function as a support structure for the mounting of various vehicle components, such as light fixtures, overhead consoles, storage compartments, electronic displays, entertainment systems, and assist handle components.
Typically, headliners are formed of a plurality of layers having different materials. It is known to form a headliner with an upper layer of fiberglass, an intermediate layer of fibrous polyethylene terephthalate (PET), and a cover layer. The upper layer of fiberglass and the PET layer are laminated together with a polyester adhesive layer cured in an oven. The cover layer has an exterior surface facing the interior of the vehicle, commonly referred to in the industry as an “A surface”. A known cover layer includes a woven or non-woven cloth. Sometimes, the cover layer includes an upper layer of foam, such as polyether-polyurethane foam. The foam of the cover layer provides a relatively pleasant soft elastic tactile “feel”. Since the foam of the cover layer is elastic, the foam may also help to reduce gaps between the headliner and other trim pieces and components installed on or adjacent the headliner. Another known headliner composite includes an upper layer of fiberglass, a layer of PET, another layer of fiberglass, and a cover layer sandwiched together. Although these known fiberglass embedded headliners have been adequate in the past, it has been found that the structural integrity of the headliners, essentially provided by the fiberglass layers, is not sufficient for modern vehicles having a variety of relatively heavy components attached thereto. Furthermore, fiberglass has some undesirably characteristics in that it is potentially irritating to the skin of the assemblers.
Another known multi-layer headliner includes an upper structural layer and a lower cover layer bonded thereto. The structural layer is a glass mat layer made of thermoplastic resin reinforced with glass fibers interspersed therein. The upper layer is commercially available under the Trademark “AZDEL” from Azdel, Inc. of Shelby, N.C. The cover layer is similar to the cover layer described above. Although this headliner is sufficient for some vehicles, the sound absorption properties is often inadequate.